I can't say that I agree with kabluton's opinion, but it can get a little cold there in the early summer. I was diving there last Saturday (6/11), and the surface temps were around 73, dropping to high 50's at around 28ffw.
The bottom line is that quarry diving isn't like reef diving, or even like sinkhole/cenote diving. The viz and be unpredictable, and the thermoclines can be pretty dramatic. That being said, I enjoy quarry diving because it gives me a chance to hone my skills without taking a long, expensive trip to a prettier place.
Here's a link to an emergency response plan that a couple of DM candidates did a few years ago that gives a pretty good feel for the site. It needs to be updated a bit, but in general it's accurate with regard to conditions and the layout of the underwater attractions.
http://www.scuba.org.vt.edu/images/Blue Stone/Blue_Stone_Resort_NC-DM.pdf
For what it's worth, I'll be doing an IDC there from July 4-14, with the IE on July 16-17, also at Bluestone. If you happen to be there during any of those days, ask Bob Outlaw, the owner, to point you in my direction. You may want to call him about local accomodations. He has a small lodge there, but I haven't stayed in it yet. Here's the link to his website:
http://www.bluedolphindive.com/bluestone.htm
If you're coming from out of town, I'd probably stay in Winston-Salem or Greensboro if you want good dining and some nightlife. Bluestone's out in the country a ways.
I use the quarry quite a bit, as it's less than an hour from Charlotte, doesn't require a membership, only costs $15, and is a good place to pick up a stray dive buddy if you're like me and like to be spontaneous about planning dive days. I tend to like the southest part of the quarry a little better late in the season when the temps improve, because the viz tends to be better and the wrecks are a little easier to see. The southwest entry point (an old gravel road leading into the pit) is used by lots of checkout divers, so it tends to have worse viz.
Hope this helps. If you need anything more specific, PM me a phone number and a time to call, and we can talk.
Safe ascents,
Grier